Introduction: The precise role of Cutibacterium in periprosthetic joint infections (PJIs) and unexpected positive intraoperative cultures (UPIC) in presumed aseptic revision total hip arthroplasty (rTHA) remains unclear. Moreover, little is known about whether there are differences in prevalence, clinical outcomes, and microbiological characteristics between Cutibacterium avidum (C. avidum) and C. acnes. This study aimed to evaluate outcomes and related factors in C. avidum and C. acnes-positive rTHA cases.

Materials and methods: We analyzed 636 culture-positive rTHA of 564 patients (men : women = 253:311, mean age: 67 years (range, 37 to 88)) with a minimum follow-up of 40 months (range, 40 to 164) between 2011 and 2021 from a single center. Cases positive for C. avidum or C. acnes were evaluated for clinical presentation, risk factors, mono- and polymicrobial detections, and antibiotic resistance patterns. The PJI cases were classified according to the International Consensus Meeting 2018 criteria. A 1:3 propensity-score matching was used to compare outcomes between pathogens.

Results: Cutibacteria were detected in 120 of 636 (18.9%) rTHA, including C. avidum in 24 of 120 and C. acnes in 96 of 120 cases. Polymicrobial infections occurred in 40 of 120 (33.3%) cases, mainly co-occurring with gram-positive pathogens. True-septic PJIs were more frequent in C. avidum (83.3%, P < 0.01), whereas C. acnes was more evenly distributed between PJI (56.4%) and UPIC (43.6%). Cutibacterium avidum was strongly associated with the direct anterior approach (DAA) (58.3 versus 17.7%, P < 0.01), higher body mass index (BMI), and American society of anesthesiologists (ASA) scores (P < 0.01). Early septic failure rates were higher in C. acnes-positive PJIs, whereas increased antibiotic resistances were observed for C. avidum.

Conclusions: We found clinically relevant differences between C. avidum and C. acnes positive rTHA. Cutibacterium avidum was more prone to cause PJI in obese patients who underwent primary DAA. The higher early septic failure in C. acnes-positive PJI cases underlines their role as a clinically important pathogen in periprosthetic hip joint infections.